textproduct: Quad Cities

KEY MESSAGES

- Slight/Enhanced Risk (level 2/3 of 5) for severe storms early Wednesday morning around sunrise, lasting through mid morning.The primary threat with these storms will be large to very large hail.

- Late Wednesday morning and through the afternoon, much of the area will have a threat for more severe storms, with the whole area under a severe threat ranging from a Slight Risk (level 2 of 5) in our northwest to a Moderate Risk (level 4 of 5) in our southeast.

- High moisture content over the area will allow for heavy rainfall with any storms late tonight, but especially through Wednesday. Flash flooding will be possible in areas that see repeating rounds of storms, especially in areas that recently saw heavy rainfall. Flood Watch has been issued for areas in West-Central Illinois.

- Quiet weather will be seen through the second half of the work week, with the pattern becoming active again this weekend and beyond.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 140 PM CDT Tue Jun 16 2026

Quiet weather will remain into this evening as weak ridging passes overhead behind the passing system that brought showers/storms early this morning. Mostly clear skies will be seen through the evening, with cloud cover increasing after sunset. Temperatures tonight will be cooler throughout, with mid 50s forecast. Increasing cloud cover overnight can be attributed to increasing moisture, as a potent wave moves in from the Northern Plains. NAEFS guidance currently has the associated surface low forecast to be at the climatological minimum, indicating that we are dealing with quite the unseasonably strong system. Ahead of this wave, we will see a strong LLJ around 45-55 KTs converging over the area. This will set the stage for storms to develop late tonight/early Wednesday morning. Confidence is increasing on the storm potential, where strong/severe storms are favored. Aside from the severe potential, we are in for a windy Wednesday due to the strong pressure gradient overhead. We can see south-southeasterly winds gusting between 30-40+ mph, especially in areas south of I-80. Below, we will dive into the timing, environment, and expected hazards with the severe storms.

Bulk of the energy and forcing moves in late tonight and near sunrise on Wednesday. Prior to storms developing, we can see showers and isolated storms after midnight. Although, around the 4-6am timeframe, we will see storms rapidly develop due to strong forcing. Deep layer shear around 55-65 KTs and MUCAPE around 1000-1500 by 7am will favor organized convection that will likely be strong to severe. Storm mode is uncertain, as guidance indicates mixed-mode convection, where supercells (embedded or semi-discrete) will be possible. With the boundary layer largely stable overnight into the morning, the main hazard should be large hail. A look at model soundings would indicate steep lapse rates and cool air aloft favoring the potential for very large hail in areas, which is also highlighted by model analog soundings. If we get more of an MCS storm mode, then we will also see a wind threat as well. PWATs between 1.25-1.50" (75th percentile of climatology) will also result in heavy rainfall potential. Any areas that see repeating rounds of storms will have a localized flash flood potential. Otherwise, frequent lightning will accompany storms through Wednesday morning. With that said, we are in for a stormy morning commute. Areas along/south of the I-80 corridor may see a break from the storms mid morning before the afternoon round, while locations north of I-80 have the chance to see repeated rounds of storms through the morning and into the afternoon hours.

Going into Wednesday late morning and through the afternoon, a secondary short wave will be moving in from northwest Iowa. This will pass through with the strong surface low and attendant cold front. As this moves in, we will see another round of showers/storms develop between 12-2pm. This will be passing during the afternoon, where strong low level warming and cooler temps aloft will result in steep lapse rates and increasing instability. This will couple with even stronger shear, resulting in another round of strong/severe storms. These look to develop largely in counties along/east of the Mississippi River, but some uncertainty does exist. With such an environment in place, supercell storms are the primary storm mode, which may develop in a disconnected line along the passing cold front. The environment is primed for all hazards, but there will be a particular focus on the tornado potential in the afternoon. Strong curvature in the low level hodographs and backed winds out ahead of the storms will favor a tornado potential, some of which may be strong. The best tornado potential will be east of the Mississippi River, especially through Western/Central Illinois. The environment overhead will also be favorable for very large hail, with model analogs highlighting the potential for >2" hail. This second round of severe storms will develop around noon local time, and generally be east of our area by 5-7PM. Coverage will start out isolated to widely scattered west of the Mississippi River, becoming more widespread along/east of the river. Stay weather aware all day!

Once again, these afternoon storms will pose a heavy rain and flash flood threat. This is supported by PWATs upwards to 1.75-2.00" (90- 99th percentile, nearing daily max), which is well above seasonal norms. Storms that develop over areas that saw rain overnight will be at the greatest risk for flash flooding, especially for areas along/north of Highway 30. WPC has much of our area in a Slight Risk (level 2 of 4) for Excessive Rainfall and Flash Flooding. When all is said and done, we are seeing the potential for 1.50-2.00"+ of rainfall for the whole event, with the axis of heaviest rainfall currently for areas along/north of the I-80 corridor.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 140 PM CDT Tue Jun 16 2026

Past Wednesday, the forecast looks to be calmer as we return to the background northwesterly flow behind the departing system. High pressure will slide in Thursday from the northwest. Pleasant temperatures will remain in place, but the active pattern looks to return as zonal flow develops over the Midwest by late in the weekend. This pattern is a typical MCS pattern where heavy rainfall would be favored by short waves passing through the zonal flow. High amounts of moisture are expected in this pattern, as well as a seasonal/typical wind threat with any zonal MCS pattern. WPC is already highlighting our region with several inches of rainfall in the later weekend to early week next week.

Ervin

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 643 PM CDT Tue Jun 16 2026

Winds will rapidly diminish to under 10 knots with sunset and will back to the southeast prior to 12z/17. After 09z/17 winds aloft will increase to over 40 knots resulting in LLWS across eastern Iowa and northern Illinois. Elevated storms will race through the area right after sunrise followed by a period of MVFR conditions. By 18z/17 conditions will improve to VFR with another round of storms expected along/east of the Mississippi River.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...Flood Watch from Wednesday morning through Wednesday evening for ILZ009-016>018. MO...None.